1. Field of the Invention
The present invention relates to a shovel that performs operations by supplying hydraulic pressure generated by a hydraulic pump, which is driven by an engine, to a hydraulic operation element.
2. Description of the Related Art
In recent years, there are many case where an engine having a turbocharger (a turbo-type supercharger) is used as an engine (an internal-combustion engine) for a hydraulic shovel. The turbocharger is designed to increase engine output by introducing pressure obtained by rotating turbine with exhaust gas from the engine.
For example, if a boom as the hydraulic operation element is started to be driven while the shovel is operated, the hydraulic load suddenly increases. Then, a load on the engine, which has been maintaining a constant revolution speed, suddenly increases. The engine is controlled to maintain the constant revolution speed against the sudden increase of the load on the engine by increasing a fuel injection amount.
Therefore, there is proposed an output control device in, for example, Patent Document 1 in order to rapidly deal with the sudden increase of the load on the engine. The output control device controls so that the engine output rapidly increase by increasing a supercharge pressure in the engine having the turbocharger when an operation causing the load on the engine to suddenly increase is detected.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2008-128107